The field of the present invention is oil well completion tools and techniques.
It is frequently advantageous to complete a well, either original, reopened or refurbished, by placing a perforated liner at the oil bearing strata surrounded by a gravel pack. Such a completion may necessitate drilling the well bore and/or undercutting the strata, removing the cuttings, placing a liner and sealing the liner to the adjacent casing. Performing these several steps independently can be time consuming and expensive.
A tool including a drill and a perforated liner has been devised whereby a well may be completed at least in preparation for the placement of a sand control adapter with a single equipment insertion. A drill bit and liner are axially associated. A fluid circulation passage extends through the assembly and may be controlled by a valve mechanism in the liner able to divert flow from the drill bit to a lateral flow through the liner. Axial splines associated between a drill pipe section and the well liner assembly along with a release mechanism to axially release the drill pipe section from the liner assembly provides for drilling with a liner in place. An under reamer is associated with the drill bit and liner assembly with the under reamer actuated by the circulation to the drill bit.
A device for sealing the end of a perforated liner to a well casing following the drilling, liner placement, cutting removal and gravel pack may be performed by a sand control adapter such as disclosed in U.S. Pat. No. 5,052,483, the disclosure of which is incorporated herein by reference.
With such an assembly, a single zone may be finished. However, in many wells, multiple productive zones may be present with interleaved nonproductive zones, water zones, desaturated zones and the like. A particular difficulty in refurbishing and reopening is the presence of desaturated zones which can rob production. Such zones can also interfere with tertiary recovery, uselessly absorbing steam. Special techniques are frequently required, such as cementing the section or covering with inner liners, for such zones.